1. Field of the Invention
This invention is in the field of multi-phase, electrical-power transformer and synchronous machine structures, and in particular, transformer and machine structures that include a rotor with stationary excitation field winding for th translation of the magnitudes of alternating currents and voltages or for electromechanical energy conversion.
2. Description of the Prior Art
Conventional electrical transformer structures are of shell- or core-type construction with magnetic circuits composed of single large magnetic cores for each phase of voltage or current. Each core provides paths for substantially all of the magnetic flux linking both the primary and secondary windings. The magnetic flux reverses direction at every point in the transformer core, causing unnecessarily large hysteresis energy loss with each cycle through the major hysteresis loop of the magnetic materials of the cores. Conventional synchronous electrical machines do not have stationary field windings, and excitation is provided by permanent magnets or by rotating field windings energized through brushes or through induced currents in rotor circuitry.
Prior-art structures are generally difficult to maintain at adequately cool temperatures because of limited access for cooling of the inner portions of large cores that are surrounded by windings threaded through those cores. Repair or replacement of the threaded windings is difficult.
In addition, conventional transformer structures generally do not provide means for adjusting power factor in either the primary or the secondary windings.